Hair-spring collet for timepieces.



PATENTED FEB. 28, 1905.

F. R. CUNNINGHAM.

HAIR SPRING GOLLET FOR TIMEPIEGES.

APPLIOATION FILED JUNE 9, 1904.

FIG].

anuowbo'c My 3 M UNITED STATES Patented February 28, 1905.

PATENT OFFICE.

FRANK R. CUNNINGHAM, OF MEDFORD, MASSACHUSETTS, ASSIGNOR TO BIGELOWV,KENNARD & 00., OF BOSTON, MASSACHUSETTS, A FIRM.

HAIR-SPRING COLLET FOR TIIVIEPlEOES.

SPECIFICATION forming part of Letters Patent No. 783,621, dated February28, 1905.

Apnlluamnn filer". June 9,1904i Serial Nov 211,850.

1'0 (NZ whom it may concern Be it known that I, FRANK R. CUNNINGHAM, acitizen of the United States, residing at Medford, in the county ofMiddlesex and State of 5 Massachusetts, have invented certain new anduseful Improvements in Hair-Spring Collets for Timepieces, of which thefollowing is a specification.

, in watches and other timepieces as heretofore constructed the innerend of the hairspring has been secured within a round hole extending ina straight line through the collet by means of a flattened taper pin.This method is objectionable for the reason that I the end of the springrequires to be bent abruptly at an angle in order to properly enter thehole in the collet, said sharp bend not only being injurious to thespring, but also exerting a disturbing influence on the uniformprogression of tension of the spring during the vibrations.

My invention has for its object to overcome these difliculties and toprovide a more perfect means of attaching the hair-spring to the collet.

\Vith this end in view my invention consists in certain other novelfeatures and details of construction, as hereinafter described andclaimed.

3 in the accompanying drawings, Figure 1 is an enlarged plan view of myhair-spring collet and part of the hair-spring which is connectedtherewith. Fig. 2 is a vertical section of the collet on the line 2 2 ofFig. 1. Fig. 3

is a plan view of the lower part of the collet, showing the groove forholding the inner end of the hair-spring.

In the said drawings, A represents a collet which is secured in theusual manner to the 4 balance-staff, (not shown,) which passesfriction-tight through the hole I). The collet is composed of two pieces10 12, Fig. 2, connected together by a screw (5 and asteady-pin 0. Eachof the pieces 10 12 is provided on its inner or meeting face with acurved groove g, forming when the two pieces are placed together arecess for the reception of the inner end of the hair-spring c. Thewalls of the grooves r are preferably tapered, as shown in Fig. 2,whereby the spring is fastened tightly 5 in place when the two parts ofthe collet are secured together by the screw ('0.

By forming the collet in two pieces and securing the spring in a recessor groove formed between the same as described I am enabled to secure auniform progression of tension of the spring in its vibrations and alsoto vary the character of the alternate vibrations as may be necessary.Furthermore, with my construction I avoid the transverse buckling of theinner end portion of the hair-spring which has heretofore been producedby wet ging the said end of the spring within a round hole in the colletand which is objectionable on account of its injury to the spring andits 5 disturbing influence on the uniformity of its vibrations.

What I claim as my invention, and desire to secure by Letters Patent, is

l. A hair-spring collet composed of two 7 pieces secured together andhaving formedin each of their inner faces a groove for receiving andholding the inner end of the hairspring.

2. A hair-spring collet composed of two pieces secured together andhaving formed in each of their inner faces a groove for receiving andholding the inner end of the hairspring; said grooves tapering in adirection perpendicular to the. plane of the balance. 30

itness my hand this 3d day of June, A. 1). 1904.

FRANK R. CUNNINGHAM. in presence 01 P. E. TESCHEMAOHER, ALioE B. FEE.

